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Topic: My bottled yeast is dead. Why? (Read 1718 times)

I had a suspicion that my dough rises for a few pizzas (and calzones) were lackluster, so on the next try I proofed the yeast first.

Nada. There was no foaming, only a slight cloudiness in the water/yeast/pinch of sugar mix.

Water temp wasn't measured with a thermometer, but I would estimate it at 100 F.

I estimate that I got a few (maybe 5) good batches of dough before my suspicion crept up.

The bottle is labled as:Fleischmann's: Active Dry Yeast, 4 Oz

Its expiration date I cannot remember at the moment, but I do know the date was in line with the other bottles on the store shelf and was a very long time from present, so I didn't think that was a factor.

I then opened a packet of what I assume is the same product, but packaged in the 7.5 gram packet.

It proofed up. Same water and yeast amount, and same water temp. Same pinch of sugar. This time there was foaming so I assumed the yeast was active. The subsequent dough rise and pizza taste were good.

Thinking of what I may have done wrong that could have caused the yeast's low performance, all I come up with is the following:

1. I refrigerated the remainder of the yeast after its very first use, but when the bottle was opened, it was at room temperature.2. I used a spoon to spoon out the yeast and weigh it for recipes. If I over spooned, the small remainder was thrown away, not put back in the bottle.3. While measuring, I sometimes left the bottle open on the counter for about a minute.

Other than that, I did not subject the yeast to bright light, high humidity, high temps, etc.

Luckily I had the backup packets of yeast. I now bought a different brand of bottled yeast (RED STAR), even though it's about 40% more expensive. I have refridgerated this bottle before it has even been opened, so that I avoid exposing yeast to air while the yeast is at room temperature.

Any ideas of what could have caused the yeast's demise?

Also, because of the possiblility of underactive or dead yeast, should I proof every single time ?

ADY does have a limited shelf life. Retail bakeries and most pizzerias will discard it if it has been opened for more than just a few weeks (30-days max.) This is one reason for the development of PADY (protected active dry yeast) as it is designed to have a better shelf life after opening/exposing to air. PADY typically has a shelf life after opening of 4 to 6-months. IDY, on the other hand, works well for up to about 3 to 6-months after opening (the shelf life will depend greatly upon how you handle the yeast after opening). After that you're on your own. Several times I have tried to use IDY that was fresh opened and partially used and stored in the fridge for 11-months only to be disappointed by poor leavening power. As for proving (as the British like to call it) or hydrating and activating the yeast as we like to call it, all ADY must be prehydrated, while prehydration/activation is optional when IDY is used. Actually, I always use IDY and I always add it directly to the flour and then mix the dough as normal and I never experience any problems, but we don't all use the same mixing procedure at home so some see better performance if the IDY is prehydrated. Experimentation will show what works best for you.BTW: Once you open a bottle of yeast you cannot exclude the air in the bottle, so oxidation takes place regardless. We have found that moisture is probably the biggest enemy to dried yeast performance/shelf life. The fridge is a good place to store it, and I would suggest that you remove it only long enough to weigh out the amount you want to use, then recap the bottle and immediately place it back into the fridge. Our main concern here is the condensation that can form on the yeast in the bottle. It only takes a couple of seconds for it to form. The individual packages are a great way to go if you live in a humid climate, or don't use the yeast very fast. The individual packets are MAP (modified atmosphere packaging) flushed to exclude most of the oxygen, providing for extended unopened shelf life, and since they are essentially a single use packet, condensation is never a problem. I buy my IDY in 500-gram packages (bags). To use it I cut a small opening in the top of the bag and pour out only what I need (extra is tossed in the trash, never returned to the bag due to the possibility of condensation. As soon as the yeast is poured from the bag, I fold the bag back down upon itself to exclude as much air/headspace as possible, secure the bag with a rubber band, and store it in the fridge. I normally get about 6-months of acceptable home performance from the yeast when handled in this manner.Tom Lehmann/The Dough Doctor

I'm of the opinion that way more yeast is killed by overly hot water, then goes bad over time. If your not using a thermometer, you aren't certain of the temperature, and I think that's where most of the fault lies. I'm using yeast that's over a year old and it works just fine. Today's modern yeast does not need hot water in order to activate, room temp or even cool water works just fine.

I'm of the opinion that way more yeast is killed by overly hot water, then goes bad over time. If your not using a thermometer, you aren't certain of the temperature, and I think that's where most of the fault lies. I'm using yeast that's over a year old and it works just fine. Today's modern yeast does not need hot water in order to activate, room temp or even cool water works just fine.

Perhaps there's a possibility that my estimate of 100 degrees F is way off and that in fact it's hot enough, perhaps 120 degress or more, to kill the yeast. In this case, however, the water temp was the same for the bottled yeast as for the packeted yeast. The packet yeast did just fine.

Fleishman's has been my yeast of preference for the last 6 years of pizza making and it's never failed me. I store it in the fridge , mix in lukewarm water, and I buy a new one every year or so. It might be sentimental. I was friends with one if the Fleishnan families girls , way back in the day. Perry

This is what I know from personal experience. First, ADY can and WILL last a DAMN long time in the fridge. How do I know? First, I have a large bag of Red Star ADY from Costco that has been in my fridge for about 2 years. It's still proofing nicely, and I get REALLY good rises out of my dough using 0.75% ADY in my recipe. So, to say that ADY has a low shelf life is beyond me. Second, I also had a bottle of Fleischmanns ADY yeast that is at least three years old. It has been sitting in the fridge, but I decided to use it a week ago when my neighbor lent me her KA mixer. She is interested in making home made pizza, so I was showing her the ropes using her own stand mixer. I also figured I could give her my 3 year old Fleischmanns ADY if it could still proof. I made a large batch of dough using the Fleischmanns, and after an hour post rise, it rose BEAUTIFULLY. It easily doubled in size and then some. So, I ended up giving her the Fleischmanns.

So, why did I switch from Fleischmanns to Red Star? Back then, I thought I was having the same problems as you: under performing yeast. I could not get a good post rest rise. I returned the Fleischmanns at Safeway for another bottle. Still, same problem. So, I went to Costcos, and I bought Red Star thinking it would be better yeast. It performed a bit better, but nothing like I was getting with IDY before. Eventually, this is what I figured out.

You need to go hotter with the water. Get a thermometer. 100F just doesn't cut it to get ADY really proofing. You need to go 120F at least. I proof ALL of my yeast mixtures at 120-125F, and within 10 minutes, I'm getting decent foam head and lots of bubbles sprouting from the bottom. I then chuck my yeast mixture into the dough as the dough kneads the other cooler water. I've never had rising problems since. And, I don't even need sugar.

I think it is important to keep in mind the distinction between the use of yeast (any form) in a home setting as opposed to a commercial setting. What Tom discussed was the use of yeast in a commercial setting where consistency of results is very important. In such a setting, I wouldn't risk getting inconsistent results in order to save a few pennies on yeast.

Modern yeast strains are more resistant to water temperature than the old yeast strains. In your case, with 0.75% ADY and using a water temperature of around 120-125 degrees F, you are likely to sustain some yeast damage but perhaps not enough to materially affect the end results, and especially so if the yeast is not kept in the hot water too long. Member November touched upon this point at Reply 13 at http://www.pizzamaking.com/forum/index.php/topic,6163.msg53065/topicseen.html#msg53065. In my case, I would be inclined not to let the ADY sit in 120-125 degrees F for too long, although at 0.75% ADY some loss of the yeast may be tolerable.

I understand what Tom is saying. However, it just doesn't jibe with my own personal experiences. That is all. Also, my mother in law does a LOT of baking, and she keeps CAKE YEAST, blocks of it, in the freezer. She gets them from a local commercial baker. I would love to get my hands on some, because her yeast just blooms like crazy. Unfortunately, she's all the way in Canada. Anyways, I was just asking her today about her cake yeast, and how long she stores it for. She says she keeps it in her freezer for up to a year until the original batch is gone, and she has never had problems with her yeast. I've heard, and I must be completely frank that I'm by far not a yeast expert (I just know what I know from my own observations and experiences), that cake yeast is fundamentally a less hardy but more robust version of ADY and IDY. From what I've seen on a Good Eats episode (I know, pretty flimsy source for an opinion, but...), cake yeast is supposedly more delicate but contains much more live yeast than ADY. Alton Brown then says in that particular episode that he never bothers with it since it just doesn't last very long. I really don't take his word, or any others, as the end-all-be-alls. It's just a point of reference for me. Anyways, all I know is, that just doesn't jibe also with what my mother-in-law's experiences with cake yeast has been so far. And she's been using the stuff for over 20 years.

For commercial operations, I agree. It's probably not a good idea to ruin a huge batch of dough with dead or under active yeast. It's probably best to make sure the yeast is fresh and active as possible.

Finally, I think it will not hurt for OP to try a higher water temp. Personally, whenever I try to proof my ADY in 100-105F water, I will not get any foam head action. It just sits there doing f--- all. In fact, I think I'm going to try it again and see. I have a very nice thermapen thermometer that I always use to gauge my proofing water. I'll report back later with details. Maybe I'm wrong here. But, still, for OP, I would suggest he try 120F and see how that helps with proofing yeast. If it's still not producing bubbles or foam head, yeah, his yeast is probably dead.

Oh, definitely cold fermented. I do at least 24 hours, but I often try for 3 days.

Ok, did a quick experiment. Must retract previous comments. 1 gram of sugar and 1 gram of yeast (Red Star ADY) went into two separate Pyrex cups. One started with ~ 120F water, the other ~ 100F. Within a few minutes, temp of water dropped by 10F. Both yeasts have sat for 5 minutes, and proofing very similar. 15 minutes out, one is at 95F, the other is at 85F. Both are still bubbling and proofing similarly. I can see lots of turbulence in the water from various angles. Not a robust foam head, but still bubbling.

So, I don't know. Maybe I'm wrong. But, I think OP should try the 120F water idea out and see if it helps. If not, at least we know 120F is just my own crack pot idea.

Ok, did a quick experiment. Must retract previous comments. 1 gram of sugar and 1 gram of yeast (Red Star ADY) went into two separate Pyrex cups. One started with ~ 120F water, the other ~ 100F. Within a few minutes, temp of water dropped by 10F. Both yeasts have sat for 5 minutes, and proofing very similar. 15 minutes out, one is at 95F, the other is at 85F. Both are still bubbling and proofing similarly. I can see lots of turbulence in the water from various angles. Not a robust foam head, but still bubbling.

So, I don't know. Maybe I'm wrong. But, I think OP should try the 120F water idea out and see if it helps. If not, at least we know 120F is just my own crack pot idea.

mililani,

As Fleischmann's and Red Star have acknowledged, a water temperature in the range you noted is an acceptable range. However, in that range, it is perhaps best to keep the prehydration time brief so as not to kill any of the yeast. Of course, if you increase the quantity above the needed value for the particular dough to be made, you might be able to use the longer prehydration time with the understanding that some of the yeast cells may give up their lives or be otherwise be compromised from a performance standpoint.

As for the cake yeast, if you do a Google search on how to store cake yeast, you will find different ways of wrapping cake yeast so that it can be frozen. Some of our members are already doing this. See, for example, Chau's post at Reply 2 at http://www.pizzamaking.com/forum/index.php/topic,14060.msg141085.html#msg141085. Again, this is not something that one would want to do in a commercial setting. Fresh yeast is the least expensive form of yeast for users of that yeast in large quantities, so it makes no sense to try to save money by freezing it to prolong its useful life.

I had a suspicion that my dough rises for a few pizzas (and calzones) were lackluster, so on the next try I proofed the yeast first.

Nada. There was no foaming, only a slight cloudiness in the water/yeast/pinch of sugar mix.

Water temp wasn't measured with a thermometer, but I would estimate it at 100 F.

I estimate that I got a few (maybe 5) good batches of dough before my suspicion crept up.

The bottle is labled as:Fleischmann's: Active Dry Yeast, 4 Oz

Its expiration date I cannot remember at the moment, but I do know the date was in line with the other bottles on the store shelf and was a very long time from present, so I didn't think that was a factor.

I then opened a packet of what I assume is the same product, but packaged in the 7.5 gram packet.

It proofed up. Same water and yeast amount, and same water temp. Same pinch of sugar. This time there was foaming so I assumed the yeast was active. The subsequent dough rise and pizza taste were good.

Thinking of what I may have done wrong that could have caused the yeast's low performance, all I come up with is the following:

1. I refrigerated the remainder of the yeast after its very first use, but when the bottle was opened, it was at room temperature.2. I used a spoon to spoon out the yeast and weigh it for recipes. If I over spooned, the small remainder was thrown away, not put back in the bottle.3. While measuring, I sometimes left the bottle open on the counter for about a minute.

Other than that, I did not subject the yeast to bright light, high humidity, high temps, etc.

Luckily I had the backup packets of yeast. I now bought a different brand of bottled yeast (RED STAR), even though it's about 40% more expensive. I have refridgerated this bottle before it has even been opened, so that I avoid exposing yeast to air while the yeast is at room temperature.

Any ideas of what could have caused the yeast's demise?

Also, because of the possiblility of underactive or dead yeast, should I proof every single time ?

I've got that exact same bottle although it's filled with another brand of IDY (I used it up years ago) and I always store my yeast in the freezer. I've never had any go bad. I get my yeast now at Costco and it's more than I'll use in 2 years or more but it'll stay fresh in an airtight container in the freezer for however long it takes me to use it.

Regarding this cake yeast...One of my hobbies is homebrewing. Yeast is used for fermenting not flour, but wort. When finished, many brewers dispose of their used yeast cake, along with other "crud" that accumulates at the bottom. Others wash and store the yeast for later use, though calculating or predicting the correct yeast "dose" when doing this can be challenging. I know there are hundreds of varieties of yeast, and it is generally known that what makes good pizza dough or bread makes terrible beer, but is the reverse true or not? It seems I may be throwing away perfectly good yeast that I could use for baking or pizza, even if I am reluctant to re-use for brewing? Seems most formula quote a dry weight yeast amount, without mention of "cell counts".

Aside- Some of the really devout hobbyists will buy a microscope and special slides and stains for counting the viable yeast in their cultures so as to accurately use the correct dose of yeast when reusing old yeast for brewing in this manner, though I haven't reached the point where I would want to buy $1000 microscope to save $20 on yeast.....yet.